Physics – Optics
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21740306e&link_type=abstract
American Astronomical Society, AAS Meeting #217, #403.06; Bulletin of the American Astronomical Society, Vol. 43, 2011
Physics
Optics
Scientific paper
High-resolution n-body simulations of galaxy-sized dark matter halos predict that the Milky Way contains numerous subhalos. Moreover, subhalos with masses greater than 106 solar masses are present within ten kiloparsecs of the center of the simulated halo, indicating that there are dark matter subhalos between the Sun and other stars within the Galaxy. When a subhalo passes in front of a star, the light from that star will be deflected by gravitational lensing, leading to a small change in the star's apparent position. This astrometric microlensing signal depends on the inner density profile of the subhalo and can be greater than a few microarcseconds for an intermediate-mass subhalo (post-stripping mass > 100 solar masses) passing within arcseconds of a star. Recent developments in high-precision astrometry make it possible to detect this unique signature of local dark matter substructure.
We develop a general formalism to calculate a subhalo's astrometric lensing cross section over a wide range of masses and density profiles, and we calculate the lensing event rate by extrapolating the subhalo mass function predicted by simulations down to the subhalo masses potentially detectable with this technique. We find that, although the detectable event rates are predicted to be low on the basis of current simulations, a large-area survey with an astrometric precision of 10 microarcseconds should observe lensing events if most of the dark matter is contained in small subhalos that have more than 1 solar mass within 0.1 pc of the subhalo centers. Furthermore, targeted astrometric observations can be used to confirm the presence of a nearby subhalo detected by gamma-ray emission. We show that, for sufficiently steep density profiles, ground-based adaptive optics astrometric techniques should be capable of detecting intermediate-mass subhalos within 100 parsecs.
Erickcek Adrienne L.
Law Nicholas M.
No associations
LandOfFree
Astrometric Microlensing by Local Dark Matter Subhalos does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Astrometric Microlensing by Local Dark Matter Subhalos, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Astrometric Microlensing by Local Dark Matter Subhalos will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1403309